This invention relates to improvements in an open-sided press. More particularly, this invention relates to an unusually light and highly useful open-sided press which incorporates an extremely simple mechanism capable of correcting possible deflection produced in the frames at the time of pressing, whereby otherwise possible deviation of the centers of the upper and lower anvils is precluded and, at the same time, the load applied to the tension plate is lessened.
Generally in an open-sided press, an upper frame and a lower frame are attached, in the manner of arms to a shank frame and a hydraulic cylinder is incorporated at the forward end of said upper frame and a table is disposed on the upper side at the forward end of the lower frame, so that an upper and a lower anvil may be attached respectively to the lower end of the rod of the cylinder and to the upper surface of the table. During the work of pressing, therefore, the pressing force produced between the anvils gives birth to repulsive force which acts on the upper and lower frames and the shank frame to cause these frames to deflect divergently in the form of a bow. Since this deflection is such that the centers of the anvils will deviate, the press system of this construction is not suitable for pressing work of exacting precision.
The invention (U.S. Pat. No. 3,303,774) completed by the present inventor has already introduced means for the correction of such deflection to the art.
The invention mentioned above is directed to giving the open-sided press a corrective mechanism, such that an auxiliary cylinder incorporated therein produces deflection in the direction opposite that of the deflection which occurs in the frames at the time of pressing and the magnitude of the opposing deflection caused by the auxiliary cylinder equals or surpasses that of the deflection in the frames. Therefore, the deflection which occurs at the time of pressing is offset by causing the auxiliary cylinder to produce a deflection in the opposite direction. In actuality, the deflection which the main cylinder produces at the forward ends of the upper and lower frames is offset by the deflection which the auxiliary cylinder produces in the opposite direction at said forward ends and, therefore, is prevented from manifesting its effect upon the operation of pressing. Nevertheless, this invention cannot prevent the deflection itself from occurring.
Furthermore the shank frame must withstand the tension resulting from the combining of the repulsive tension produced at the time of pressing and the tension produced by the auxiliary cylinder and, therefore, requires strength which can be obtained only by use of steel plate of sufficient thickness. Thus, it is not possible to reduce the weight of the unit by reducing the weight of the shank frame.
One object of the present invention is to provide an open-sided press which makes it possible to accomplish the desired fabrication by pressing with high precision and perfect freedom from the deflection which would otherwise occur at the time of pressing.
Another object of the present invention is to provide an open-sided press which is light in weight and simple in construction.